Ingredients:

  • 1 cup (226g) unsalted butter, softened
  • 1 1/4 cups (250g) granulated sugar
  • 1 large egg, room temperature
  • 1 tablespoon pure vanilla extract
  • 2 3/4 cups (345g) all-purpose flour, spooned and leveled
  • 2 teaspoons cornstarch
  • 1 teaspoon baking soda
  • 1/2 teaspoon cream of tartar
  • 1/2 teaspoon fine sea salt
  • 1/4 cup (50g) granulated sugar (for rolling)

Instructions:

  1. Preheat your oven to 350°F (175°C) and line two large baking sheets with parchment paper or silicone mats.
  2. In a large bowl or stand mixer, beat the softened butter and 1 1/4 cups of sugar together on medium-high speed for 3 minutes until pale and whipped. Add the egg and vanilla extract, beating until fully incorporated.
  3. In a separate bowl, whisk together the flour, cornstarch, baking soda, cream of tartar, and salt. Turn the mixer to the lowest setting and gradually add the dry ingredients to the wet ingredients, mixing only until the last streak of flour disappears.
  4. Scoop rounded tablespoons of dough (about 1.5 to 2 tablespoons each) and roll them into smooth balls. Roll each ball in the small bowl containing the extra 1/4 cup of sugar until fully coated.
  5. Place dough balls on the prepared baking sheets at least 2 inches apart. Bake for 9–11 minutes. The edges should be set but the centers should still look slightly underbaked and puffy.
  6. Allow the cookies to cool on the hot baking sheet for at least 5-10 minutes to firm up before transferring to a wire rack.